The Cooperative Cataract Research Group (CCRG) is an American research consortium made up of 12 funded and 11 unfunded laboratories working in basic lens/cataract research. It is the purpose of the Consortium to further research on human cataract formation with a particular focus on the so-called "senile" cataract. During the past three years, the Consortium has dramatically increased the number of human lenses (clear and cataractous) availabe for laboratory research. It has developed, tested and implemented a system for classifying cataractous changes in the lens and also has used PROPHET, a NIH biomedical computer resource, for the management of cataract research data. This renewal application proposes to continue the research efforts of the Consortium by 1) enhancing the quality of classification photographs derived from each of the participating laboratories, 2) using a comparatively inexpensive, new stereoscopic camera to photograph extracted cataracts in laboratories presently without photographic equipment, 3) testing the basic assumption that each anatomically unique form of human "senile" cataract has an equally unique biochemical, biophysical, physiological and/or anatomical identity, 4) developing techniques for microdissecting human cataracts into clear and opaque zones which can be analyzed separately, 5) extending the cataract classification system to in vivo use, and 6) furthering non-invasive techniques of assessing human cataractogenesis in vivo. By understanding the mechanisms of cataract formation it may be possible to develop a means of slowing or preventing the formation of senile cataract in man. If achieved, this would reduce the number of cataract extractions need in the United States, a number now exceeding 500,000 per year.